Port Switching Printer Sharing93Port Switching Printer SharingTo support printer sharing, 10/100Base-T Ethernet Interfaceprinters automatically switch among all attached ports (serial port,the twinax or coax port, or the Ethernet network port). Basically, theprinter prints jobs for one port until no new jobs appear and the port“times out”. The printer then switches to the next port and does thesame thing.To change the default “time out” value for a port, update theTIMEOUT value for the port on the appropriate menu (SerialInterface, Ethernet, Twinax Interface, or Coax Interface).Handling z/OS Connectivity ProblemsIf you encounter problems when “ping”-ing a network printer fromz/OS, here is how to resolve them.Ping is not SuccessfulIf the “ping” is not successful, verify the following:• The printer is powered on.• The IP address is unique in the TCP/IP network.If the IP address of the z/OS system is not unique, see yournetwork administrator to resolve the IP address problem.• The Maximum Transmission Unit (MTU) size of the IP packetfor the z/OS system is equal to the MTU size of the printer. Forinformation about the values recommended for the z/OSsystem, see “Modify the TCP/IP Profile in z/OS” on page 81.To change the MTU size for the z/OS system, change theGATEWAY statement in the z/OS TCP/IP profile, and restartTCP/IP to pick up the changes.You cannot change the MTU size on a 10/100Base-T EthernetInterface printer. The MTU size is fixed at 1024 bytes.If these items are all in order, consult your TCP/IP networkadministrator about a possible network problem.
